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authorKrzysztof Gogolewski <krzysztof.gogolewski@tweag.io>2020-06-15 19:59:46 +0200
committerBen Gamari <ben@smart-cactus.org>2020-06-17 16:22:03 -0400
commit6cb84c469bf1ab6b03e099f5d100e78800ca09e0 (patch)
tree5dd883d7fd637093b60b7a62ecdb58389873bb0f /compiler/GHC/Stg
parent40fa237e1daab7a76b9871bb6c50b953a1addf23 (diff)
downloadhaskell-6cb84c469bf1ab6b03e099f5d100e78800ca09e0.tar.gz
Various performance improvements
This implements several general performance improvements to GHC, to offset the effect of the linear types change. General optimisations: - Add a `coreFullView` function which iterates `coreView` on the head. This avoids making function recursive solely because the iterate `coreView` themselves. As a consequence, this functions can be inlined, and trigger case-of-known constructor (_e.g._ `kindRep_maybe`, `isLiftedRuntimeRep`, `isMultiplicityTy`, `getTyVar_maybe`, `splitAppTy_maybe`, `splitFunType_maybe`, `tyConAppTyCon_maybe`). The common pattern about all these functions is that they are almost always used as views, and immediately consumed by a case expression. This commit also mark them asx `INLINE`. - In `subst_ty` add a special case for nullary `TyConApp`, which avoid allocations altogether. - Use `mkTyConApp` in `subst_ty` for the general `TyConApp`. This required quite a bit of module shuffling. case. `myTyConApp` enforces crucial sharing, which was lost during substitution. See also !2952 . - Make `subst_ty` stricter. - In `eqType` (specifically, in `nonDetCmpType`), add a special case, tested first, for the very common case of nullary `TyConApp`. `nonDetCmpType` has been made `INLINE` otherwise it is actually a regression. This is similar to the optimisations in !2952. Linear-type specific optimisations: - Use `tyConAppTyCon_maybe` instead of the more complex `eqType` in the definition of the pattern synonyms `One` and `Many`. - Break the `hs-boot` cycles between `Multiplicity.hs` and `Type.hs`: `Multiplicity` now import `Type` normally, rather than from the `hs-boot`. This way `tyConAppTyCon_maybe` can inline properly in the `One` and `Many` pattern synonyms. - Make `updateIdTypeAndMult` strict in its type and multiplicity - The `scaleIdBy` gets a specialised definition rather than being an alias to `scaleVarBy` - `splitFunTy_maybe` is given the type `Type -> Maybe (Mult, Type, Type)` instead of `Type -> Maybe (Scaled Type, Type)` - Remove the `MultMul` pattern synonym in favour of a view `isMultMul` because pattern synonyms appear not to inline well. - in `eqType`, in a `FunTy`, compare multiplicities last: they are almost always both `Many`, so it helps failing faster. - Cache `manyDataConTy` in `mkTyConApp`, to make sure that all the instances of `TyConApp ManyDataConTy []` are physically the same. This commit has been authored by * Richard Eisenberg * Krzysztof Gogolewski * Arnaud Spiwack Metric Decrease: haddock.base T12227 T12545 T12990 T1969 T3064 T5030 T9872b Metric Increase: haddock.base haddock.Cabal haddock.compiler T12150 T12234 T12425 T12707 T13035 T13056 T15164 T16190 T18304 T1969 T3064 T3294 T5631 T5642 T5837 T6048 T9020 T9233 T9675 T9872a T9961 WWRec
Diffstat (limited to 'compiler/GHC/Stg')
-rw-r--r--compiler/GHC/Stg/Lift/Monad.hs2
-rw-r--r--compiler/GHC/Stg/Unarise.hs1
2 files changed, 1 insertions, 2 deletions
diff --git a/compiler/GHC/Stg/Lift/Monad.hs b/compiler/GHC/Stg/Lift/Monad.hs
index 21097cc59f..dcfa0ce644 100644
--- a/compiler/GHC/Stg/Lift/Monad.hs
+++ b/compiler/GHC/Stg/Lift/Monad.hs
@@ -34,7 +34,7 @@ import GHC.Utils.Outputable
import GHC.Data.OrdList
import GHC.Stg.Subst
import GHC.Stg.Syntax
-import GHC.Core.Type
+import GHC.Core.Utils
import GHC.Types.Unique.Supply
import GHC.Utils.Misc
import GHC.Types.Var.Env
diff --git a/compiler/GHC/Stg/Unarise.hs b/compiler/GHC/Stg/Unarise.hs
index 3e5d2f3101..e78a58894d 100644
--- a/compiler/GHC/Stg/Unarise.hs
+++ b/compiler/GHC/Stg/Unarise.hs
@@ -220,7 +220,6 @@ import GHC.Builtin.Types
import GHC.Types.Unique.Supply
import GHC.Utils.Misc
import GHC.Types.Var.Env
-import GHC.Core.Multiplicity ( pattern Many )
import Data.Bifunctor (second)
import Data.Maybe (mapMaybe)